Steric and electronic tuning of atropisomeric amino alcohol type ligands with a 1-arylpyrrole backbone

The synthesis of new, trifluoromethyl group containing atropisomeric amino alcohols and their application in enantioselective diethylzinc additions to aldehydes is described. A significant improvement of the enantioinductive effects of the new ligands by increasing the Brønsted acidity and bulkiness of the triarylcarbinol moiety is also reported. Tuning was achieved by the introduction of phenyl substituents containing two trifluoromethyl groups onto the α-carbon of the tertiary alcohol part of the ligand. The application of the new catalysts provided 1-(substituted phenyl)propanols with excellent enantiomeric purities.